A Review on the Development of Tunable Graphene Nanoantennas for Terahertz Optoelectronic and Plasmonic Applications

Abstract

Exceptional advancement has been made in the development of graphene optical nanoantennas. They are incorporated with optoelectronic devices for plasmonics application and have been an active research area across the globe. The interest in graphene plasmonic devices is driven by the different applications they have empowered, such as ultrafast nanodevices, photodetection, energy harvesting, biosensing, biomedical imaging and high-speed terahertz communications. In this article, the aim is to provide a detailed review of the essential explanation behind graphene nanoantennas experimental proofs for the developments of graphene-based plasmonics antennas, achieving enhanced light–matter interaction by exploiting graphene material conductivity and optical properties. First, the fundamental graphene nanoantennas and their tunable resonant behavior over THz frequencies are summarized. Furthermore, incorporating graphene–metal hybrid antennas with optoelectronic devices can prompt the acknowledgment of multi-platforms for photonics. More interestingly, various technical methods are critically studied for frequency tuning and active modulation of optical characteristics, through in situ modulations by applying an external electric field. Second, the various methods for radiation beam scanning and beam reconfigurability are discussed through reflectarray and leaky-wave graphene antennas. In particular, numerous graphene antenna photodetectors and graphene rectennas for energy harvesting are studied by giving a critical evaluation of antenna performances, enhanced photodetection, energy conversion efficiency and the significant problems that remain to be addressed. Finally, the potential developments in the synthesis of graphene material and technological methods involved in the fabrication of graphene–metal nanoantennas are discussed.

A Review on Graphene-Based Light Emitting Functional Devices

“…The realization of ultrafast plasmons-based optical signal source at the nanoscale is considered as a longstanding goal, the potential of the graphene-based emitter to revolutionize optoelectronics, thus allowing ultrafast optical signal processing for communication [ 49 ]. When the electron beam is exposed to the optically excited surface plasmons of graphene, the unidirectional, chromatic, and tunable emission from IR to X-ray was realized from the graphene [ 50 , 51 , 52 ]. The theoretical investigation and experimental demonstration of this mechanism predict the existence of plasmons at VIS and IR wavelengths [ 53 ].…”

An Optically Tunable THz Modulator Based on Nanostructures of Silicon Substrates

“…The photocarrier concentrations of the four models at 60 mW/mm 2 are listed in Table 2, which are calculated from Equation (1). The enhanced multireflection between the surface nanostructures and the specific surface area enables strong light absorption.…”

“…Terahertz (THz) radiation (0.1~10 THz) triggers a great number of intriguing and complex physical, biological, and chemical phenomena. It consequently possesses wide practical application prospects in communications, spectroscopy, and imaging [1][2][3][4][5][6][7]. For THz imaging purposes, a THz spatial light modulator (SLM) is involved, which requires the THz modulator to be fast and efficient.…”

Dynamic Absorption Enhancement and Equivalent Resonant Circuit Modeling of Tunable Graphene-Metal Hybrid Antenna

“…The dispersion relation of the graphene presented by Equation (29) can be reduced to the ordinary TL model dispersion relation as, βp = √ LC, when the resistance R = 0 is considered in Equation (29). Applying the Fabry-Perot type resonator condition on graphene hexagon having an effective length, Equation 29becomes…”

“…The absorption efficiency that was attained at the infrared region is tuned from 3% to 30% with tightly packed graphene nanodisks. Furthermore, various studies are reported by utilizing different graphene nanostructures to enhance the absorption along with enhancement of electric field [23,25,29]. Gric et al [30], use the approach of photo-conductive antennas that is based on the optimized plasmonic nanostructure to numerically study the absorption enhancement in nanocylinders, where the absorption amplituide and resonant wavelength can be affected by the thickness and separation of nano cylinders.…”